Effects of UV‐irradiation on the nonisothermal crystallization kinetics of polypropylene

The influences of UV‐induced photodegradation on the nonisothermal crystallization kinetics of polypropylene (PP) were investigated by differential scanning calorimetry. The Avrami analysis modified by Jeziorny, Ozawa method, and a method modified by Liu were employed to describe the nonisothermal crystallization process of unexposed and photodegraded PP samples. Kinetics studies reveal that the rates of nucleation and growth may be affected differently by photodegradation. A short‐term UV‐irradiation may accelerate the overall nonisothermal crystallization process of PP, but a long‐term UV‐irradiation should impede it. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci, 2006     

Microbial growth control in water hydraulic systems by conventional filtration

As a service to readers who understand German, French or Spanish better than English, the abstract of the research article in this issue follows in these languages.     

基于Kern-Seaton模型结合Capdeville生物膜增长体系建立的微生物污垢模型

为研究换热设备生物污垢的形成过程,将Capdeville生物膜增长体系引入Kern-Seaton模型,建立了一个新的微生物污垢模型。采用铁细菌和管式换热装置对模型进行了实验验证。结果表明：除诱导期外,新建的微生物污垢热阻模型的计算数据和实验数据的相对误差小于20%。     

Optical parameters and absorption studies of UV‐irradiated azo dye‐doped PMMA films

PMMA and PMMA films doped with different contents of azo dye have been made by using the casting technique. The absorption spectral analysis showed that the doped films have two absorption bands attributed to the π‐π* and n‐π* transition of chromophore groups. These bands disappear upon UV‐irradiation, suggesting that the studied system undergoes a photo degradation process. The absorption coefficient and optical energy gap (E_g) have been obtained from the absorption edge in the 200–900 nm range. It was found that E_g decreases with increasing doping levels, whereas it increases with increasing irradiation time. The width of the tail of localized states in the band gap (ΔE) was evaluated using the Urbach edge method. Some optical parameters were determined from the reflection and transmission spectra in the spectral range of 200–2500 nm. The dependence of the refractive index on irradiation time and doping level have been discussed. It was found that the photo‐induced refractive index changes are very large. These changes suggest the applicability of the studied system in optical devices. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

UV‐protecting and antibacterial finishing of cotton knits

This article deals with enhancing the UV‐protecting properties as well as the antibacterial activity of knitted cotton fabrics against two kinds of bacteria: gram‐positive bacteria (G +ve), i.e., Staphylococcus aureus (S. aureus), and gram‐negative bacteria (G ?ve), i.e., Escherichia coli (E. coli). Results showed that the extent of improvement in the UPF values are determined by: the fabric structure, i.e., Interlock > Pique > Parasol, pretreatment history, i.e., gray > scoured > bleached, type of softening agent, incorporation of the UV‐absorber in the softening bath as well as sequence of addition, in addition to the nature of the deposited metal‐oxide, i.e., Cu > Zr > Zn ? Al ≈ none. On the other hand, the antibacterial activities of the treated substrates against G +ve and G ?ve bacteria are outstandingly improved by using the proper: fabric structure, i.e., Parasol > Interlock > Pique, state of the untreated substrate, i.e., bleached > gray, finishing additives and regime, i.e., soft finishing (using polysiloxame softener—Adasil® SM) and UV‐protecting (using UV‐absorber, Tinofast® CEL) in one step > Tinofast® CEL‐finish > Adasil® SM‐finish > full‐bleaching, as well as deposited metal oxide, i.e., Zn > Cu > Zr > Al > none. Combined soft‐finishing and UV‐cutting as well as in situ deposition of proper metal oxides, onto and/or within the knitted substrates, options exhibited both an excellent UV‐protection and prominent antibacterial activities. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Synthesis and kinetic studies of UV‐curable urethane‐acrylates

The UV‐curable urethane‐acrylates based on 2‐hydroxyethyl methacrylate (HEMA)‐terminated polyurethane (PU) for lithographic and coating applications are investigated in this study. Series of PU prepolymers were made from 4,4‐diphenyl methane diisocyanate (MDI), poly(propylene oxide) glycol (PPG 400), poly(butylene adipate)glycol (PBA 500), or poly(tetramethylene oxide) glycol (PTMO 1000) and are terminated with HEMA. The 2,2‐azobisisobutyronitrile (AIBN) was used as a UV‐initiator under air atmosphere. The curing kinetics of HEMA‐terminated PU film were studied. The curing analysis, using FTIR and reaction kinetics, indicate the reaction rate equation correlates well with the film thickness [T], initiator concentration [I], unreacted double bond concentration [C?C], and exposed energy [E] of the reaction system. The kinetic rate equation for the UV‐curable reaction can be written as © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91: 3162–3166, 2004     

UV‐Triggered Optical Response and Oxygen Scavenging Ability of a Water‐Soluble Poly(N,N‐dimethylacrylamide‐co‐2‐vinylbenzylanthraquinone) Copolymer

A vinyl‐modified anthraquinone (AQ) derivative (Vinyl‐AQ) is synthesized through a palladium‐mediated Suzuki coupling reaction between vinylphenylboronic acid and 2‐chloromethylanthraquinone and, subsequently, copolymerized with N,N‐dimethylacrylamide (DMAM) through free radical copolymerization in organic solvent. The chemical structure of the resulting water‐soluble copolymer, P(DMAM‐co‐AQ), is verified using techniques such as proton nuclear magnetic resonance, attenuated total reflection‐infrared spectroscopy, thermogravimetric analysis, and UV–vis spectroscopy. The evolution of the oxygen scavenging abilities of aqueous P(DMAM‐co‐AQ) solutions after UV irradiation is monitored as a function of UV irradiation time, concentration of AQ moieties, and pH. The copolymer is proved an effective UV‐triggered oxygen scavenger, leading to dissolved oxygen contents below 1 ppm for the optimized experimental conditions. This behavior is related with the appearance of novel chemical species with interesting optical properties, as suggested by the respective evolution of the UV–vis absorption and photoluminescence spectra after UV irradiation.     

Curing and combustion properties of a PU‐coating system with UV‐reactive phosphazene

A UV‐curable polyurethane (PU)‐coating system containing phosphorus is formulated by the combination of photoinitiator, PU acrylate oligomer, and UV‐reactive phosphazene monomer. PU acrylate oligomer is prepared by the addition of 2‐hydroxyethylmethacrylate (HEMA) to NCO‐terminated PU prepolymer. UV‐reactive phosphazene monomer is derived from the HEMA substitution reaction to hexachlorocyclotriphosphazene (NPCl₂)₃. The curing reaction of this PU‐coating system is carried out by UV irradiation. The resultant UV‐cured PU‐coated films demonstrated better performance properties than those of original UV‐cured PU acrylate (UV‐PU) without UV‐reactive phosphazene monomer. Furthermore, their thermal properties are investigated by a thermogravimetric analyzer and a dynamic mechanical thermal analyzer, respectively. The combustion behaviors of these UV‐cured PU‐coated films are evaluated by the measurements of a limiting oxygen index and a cone calorimeter. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 1980–1991, 2002     

Crystallization behavior and UV‐protection property of PET‐ZnO nanocomposites prepared by in situ polymerization

The aim of this study was to investigate the crystallization behavior and UV‐protection property of polyethylene terephthalate (PET)‐ZnO nanocomposits. PET‐ZnO nanocomposites containing 0.5–3.0 wt % of ZnO were successfully synthesized by in situ polymerization. The Fourier transformed infrared (FTIR) spectroscopy indicated the silane coupling agent was anchored onto the surface of ZnO. Scanning electron microscope (SEM) images showed ZnO particles were dispersed homogeneously in PET matrix with amount of 0.5–1.0 wt %. Differential scanning calorimetry (DSC) results exhibited that the incorporation of ZnO into PET resulted in increase of the melting transition temperature (T_m) and crystallization temperature (T_c) of PET‐ZnO nanocomposites. The crystallization behavior of PET and PET‐ZnO nanocomposites was strongly affected by cooling rate. ZnO nanoparticles can act as an efficient nucleating agent to facilitate PET crystallization. UV–vis spectrophotometry showed that UV‐ray transmittance of PET‐ZnO nanocomposites decreased remarkably and reached the minimum value of 14.3% with 1.5 wt % of ZnO, compared with pure PET whose UV‐ray transmittance was 84.5%. PET‐ZnO nanocomposites exhibited better UV‐protection property than pure PET, especially in the range of UVA. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Investigation on the formation mechanisms of hydrogels made by combination of γ‐ray irradiation and freeze‐thawing

Hydrogels based on poly(vinyl alcohol) (PVA)/water‐soluble chitosan (ws‐chitosan)/glycerol were prepared by γ‐ray irradiation, freeze‐thawing, and combination of γ‐ray irradiation and freeze‐thawing, respectively. The influence of freeze‐thawing cycles, the irradiation doses, and the sequence of freeze‐thawing and irradiation processes on the rheological, swelling, and thermal properties of these hydrogels was investigated to evaluate the formation mechanisms of hydrogels made by combination of irradiation and freeze‐thawing. For hydrogels made by freeze‐thawing followed by irradiation, the physical crosslinking is destroyed partially while chemical crosslinking is formed by irradiation. However, the chemical crosslinking density reduces with the increase of freeze‐thawing cycles. Hydrogels made by irradiation followed by freeze‐thawing bear less degree of physical crosslinking with the increase of irradiation dose for the increased chemical crosslinking density. It is found that these hydrogels own larger swelling capacity and better transparent appearance than those made by freeze‐thawing followed by irradiation. Moreover, the former hydrogels have larger mechanical strength than the latter at low freeze‐thawing cycles. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Preparation and characterization of UV‐grafted ion‐exchange textiles in continuous electrodeionization

Ion‐exchange textiles (IETs) suitable for use in continuous electrodeionization (CEDI) stacks were prepared using the ultraviolet (UV)‐induced grafting of acrylic acid and sodium styrene sulfonate for cation‐exchange textiles, or 2‐hydroxyethyl methacrylate and vinylbenzyl trimethyl ammonium chloride for anion‐exchange textiles, onto nonwoven polypropylene fabric using benzophenone as photoinitiator. Although the ion‐exchange capacity (2.2 meq g^?1) of the prepared strong acid cation‐exchange textile was lower than that of IRN77 strong acid cation‐exchange resin (4.2 meq g^?1), the overall rate constant of IET was very high due to its low crosslinking and high specific surface area. There was no significant difference between the two different media in terms of the Co(II) removal rate. Furthermore, the current efficiency for IETs was higher than that of IRN77 cation‐exchange resin during a CEDI operation, with efficiencies of 60% and 20%, respectively. The IET also showed the faster exchange kinetics. Therefore, IETs prepared in this study proved to have desirable ion‐conducting characteristics within the CEDI systems. Also this study revealed that the primary removal mechanism in CEDI is the transport of ions through a medium and not the ionic capacity of a medium. Copyright © 2004 Society of Chemical Industry     

Preparation and characterization of UV‐curable MPS‐modified silica nanocomposite coats

A series of UV‐curable nanocomposites were prepared with 3‐(trimethoxysilyl) propyl methacrylate (MPS) modified nanosilica under the initiation of 2,2‐dimethoxy‐1,2‐diphenylethan‐1‐one. It was found that MPS‐modified nanosilica together with free MPS could form transparent nanocomposite coats. As the particle size of nanosilica increased, the photopolymerization rate, final double bond conversion, and tack‐free time of nanocomposites increased while the surface roughness, glass‐transition temperature, and UV absorbance of nanocomposites decreased. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 2274–2281, 2005     

Kinetic behavior of photo‐polymerization of UV‐curable resins with carboxylic acid and amino groups

Photo‐polymerization behaviors of bisphenol‐A epoxy diacrylate (EPA) and six kinds of EPA‐derived resins containing different amounts of carboxylic acid, urethane, amide, and imide groups were studied by a photo differential scanning calorimetry. The dark polymerization was performed and pseudo‐steady state assumption of growing radicals was made to obtain the kinetic constants for propagation, bimolecular termination, monomolecular termination, and the concentration of growing radicals of different resins as a function of extent of reaction. Compared with EPA, it was found that the rate of polymerization and kinetic constants of the six resins were relatively small because the mobility of reacting species in resins was restricted by carboxylic acid, urethane, amide, and imide groups. Finally, three different photo‐initiators were used to initiate the polymerization, and their kinetic behaviors were compared. The effect of tertiary amine group of photo‐initiator on the rate of polymerization of resins having carboxylic acid group and the initiator efficiency were discussed. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

头孢菌素C发酵液膜过滤的评价指标及其控制

发酵液的过滤澄清是头孢菌素C（CPC）分离与提纯的首要环节,对CPC产品的质量、成本和生产进度等有着很大的影响。本文针对CPC发酵液的膜过滤过程,分别给出了过滤过程评价指标和滤液质量评价指标。通过对部分评价指标的分析,讨论了影响各指标水平的具体因素,并建立起了有关参量间的量化模型,从而为滤液质量的控制与生产过程的优化提供了途径和方法。     

生物砂滤去除微污染水源水浊度特性与机理研究

研究了生物砂滤柱对微污染水源水浊度的去除效果,分析了水温、进水浊度和有机物指标等对出水浊度的影响。结果表明,自然挂膜滤柱较接种挂膜滤柱对浊度的去除效果更佳;在常温(22～26℃)和低温(15℃以下)条件下,生物砂滤柱对浊度的去除率分别为76%～84%和58%～79%。相同温度条件下,进水浊度与出水浊度存在一定的相关性,相关系数R2为0.548 7;通过对进水CODMn、UV254与出水浊度的研究表明,有机物指标越高,则出水浊度越高。生物砂滤柱对浊度的去除可以总结为机械沉淀、生物絮凝、生物氧化作用等几个方面。采用生物砂滤柱处理微污染水源水,能够有效去除水中的浊度。     

Preparation of silica/polyurethane nanocomposites by UV‐induced polymerization from surfaces of silica

UV‐curable nanocomposites were prepared by the in situ photopolymerizaton with nanosilica obtained from sol–gel process. The photoinitiator 2‐hydroxy‐2‐methyl‐1‐phenylpropane‐1‐one (1173) was anchored onto the surface of the nanosilica with or without methacryloxypropyltrimethoxysilane (MAPS) modification. The photopolymerization kinetics was studied by real‐time Fourier transform IR (RTIR), and the microstructure and properties of the nanocomposite were investigated using transmission electron microscopy and UV–visible (UV–vis) transmistance spectra. RTIR analysis indicated that the nanocomposites without MAPS had higher curing rates and final conversion than those with MAPS. The nanocomposites with an uniformal dispersion of nanosilica had high UV–vis transmittance. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Preparation and evaluation of epoxy methacrylate UV‐curable coatings containing phthalazinone

Epoxy methacrylate resin (EMA) UV‐curable coatings exhibit high reactivity, low viscosity and excellent chemical resistance in environmentally friendly coatings. A novel EMA containing phthalazinone moieties for high temperature resistant UV‐curable coatings was synthesized. The formulations were cured with hexanediol diacrylate (HDDA) and trimethylol propane triacrylate (TMPTA) as reactive diluents promoted by a photoinitiator, and then interpenetrating polymer networks were generated. The mechanical, chemical and thermal properties of the clear coatings were characterized using Chinese National Standard methods (GB). EMA was used with UV radiation curing in combination with 6.7 wt% of HDDA and 13.4 wt% of TMPTA, and the properties of the cured films were as follows: pencil hardness of 5 H, 30% NaOH resistance for 30 days, 15% HCl resistance for 10 days, 3% NaCl resistance for 30 days and 5% weight loss temperature of 300.5 °C. EMA UV‐curable coatings containing phthalazinone exhibit excellent chemical and thermal stability, and could be potential candidates for UV‐curable zero volatile organic compound coatings applied in the fields of salt spray corrosion, strong radiation and high‐temperature resistance. Copyright © 2009 Society of Chemical Industry     

Synthesis of UV‐curable difunctional silane monomer based on 3‐methacryloxy propyl trimethoxysilane (3‐MPTS) and its UV‐curing characteristics and thermal stability

In the present investigation, silicon containing UV‐curable difunctional monomer was synthesized by reacting 3‐methacryloxy propyl trimethoxysilane (3‐MPTS) with acrylic acid using anhydrous ether as a solvent under inert atmosphere. The synthesized acryloxymethacryloxy silane monomer was characterized by FTIR, ¹H‐NMR, and ¹³C‐NMR spectroscopy. The silane monomer along with 4 wt % photoinitiator (Darocure 1173) was cured under UV‐light for different exposure time. The curing characteristic of the monomer was investigated using FTIR spectroscopy. The conversion of the double bond due to curing has been evaluated from the peak intensity of the C?C double bond (at 1636 cm^?1) in the FTIR spectrum considering the peak intensity at 1720 cm^?1 due to C?O as internal standard. The maximum double bond conversion is observed to be 72%. The optimum cure time for the silane monomer has been estimated to be 7.8 sec. The UV‐cured sample decomposes at 440°C. The char residue is 35% at 700°C. The synthesized UV‐curable silane monomer may be useful for UV‐coating formulations, for fabrication of 3D‐objects by lithographic technique and as a precursor for organic–inorganic hybrid materials. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010